Update app.py

app.py

@@ -203,8 +203,9 @@ ax.set_ylabel(selected_target)
 
 # Show regression line if selected
 show_regression = st.checkbox('Show Regression Line')
-if show_regression and selected_feature in X.columns and selected_target == 'MedHouseVal':
+if show_regression and selected_feature in df.columns and selected_target == 'MedHouseVal':
     X_feature = df[[selected_feature]]
+    y = df[selected_target]
     model_feature = LinearRegression()
     model_feature.fit(X_feature, y)
     line = model_feature.predict(X_feature)